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Height issue in 3d mesh in Cloud

Hi Folks

 

I’m trying to share my point cloud and 3d mesh from a project I have processed on desktop. The project was processed with GCPs in terms of our local coordinate system (Poverty Bay 2000) which is available in pix4d. 

I have uploaded the project files (without processing) and then uploaded the point cloud .las and mesh .Obj and can view them in the 3d window.

The issue is the heights for the 3d mesh are incorrect and are different to the desktop mesh. The cloud .las has come in correctly.

It looks like the textured mesh has been converted to WGS84 so maybe that is the issue?

Hi Tim. The cloud only supports WGS84 currently so that is why the change in project CS. We are looking into displaying in the project CS declared in the p4d file and local project so that may be improved in the future. Could the difference in values be that the units of measurement are not the same? i.e the cloud reporting meters and the local project in feet? 

How significant are the differences in hights? can you send examples and screenshots?

Hi Holden The units for the height datum is in metres, it is a local datum that approximates mean sea level.

 

Below are two images showing heights and coordinates of the same point in the cloud data and the 3d mesh.

The 3d mesh is around 27m lower than the cloud data. The cloud data heights are correct. The mesh horizontal coordinates are way off too

 

 

 

 

 

 

 

It looks like this is due to the fact that the mesh and pointcloud are actually vertically offset in the model. You can confirm this by displaying both simultaneously, one is loaded above the other. Im not aware of any other reports of this happening. I would try reprocessing the dataset to see if the problem remains after.